In the vascular therapy of an artery or a vein, treatments of an aneurysm and bypassing, abscission and anastomosis of a blood vessel are mainly conducted for arteries, and treatments of a varix, treatments using a catheter, shunt, exscission and ablation with laser or radio wave are conducted for veins.
With respect to the aneurysm among the therapies set forth above, no symptoms are found even when an aneurysm without rupture is present. However, when the aneurysm is ruptured, internal hemorrhage takes place, and this causes a serious result leading to danger on life, occasionally.
For example, in the case of a brain aneurysm, when an aneurysm having the possibility of rupture is found, therapies such as a therapy in which the flow of the blood stream into the aneurysm is stopped by clipping the base part of the aneurysm from the outside, and a therapy in which the flow of the blood stream into the aneurysm is prevented by placing a coil at the inside of the aneurysm or by placing various types of stents at the inside of a blood vessel at the base part of the aneurysm, have been widely conducted.
An aneurysm has a shape protruded at the outside of a blood vessel like a hill slope. For example, it is desirable from the standpoint of preventing rupture of the aneurysm that clipping is made at a position closer to the foot of the hill slope. However, when the position of the clipping is excessively close to the foot of the hill slope as the shape of the aneurysm, narrowing or strain tends to be formed in the vascular membrane in the vicinity of the position of the clipping, or change in the steric form tends to take place in the vicinity of the aneurysm due to bending. As the result, the form of the blood stream becomes unstable, and the smooth flow of the blood is adversely affected. Similarly, when a coil or a stent is used, the form of the blood stream becomes unstable after the operation depending on the size of the coil or the stent or the position where the coil or the stent is placed.
In the case of the operation on an un-ruptured aneurysm, even if it is confirmed that nothing abnormal is found on the shape and the flow of the blood stream in a condition that the portion of the operation is opened or in a condition that a catheter is inserted for the use of a clip, a coil or a stent, it is not possible to confirm during the operation the stability of the shape of the blood vessel after the operation since the tension on flexible thin blood vessels changes when the operation is completed after the portions opened during the operation are anastomosed and the catheter is removed. When an adverse effect on the smooth flow of the blood is found, the operation is conducted again, and the entire treatment on the aneurysm such as clipping must he conducted again.
In such a case, it would be a great merit for both of the patient and the operator, if it is possible to conduct a preoperative simulation to confirm that no adverse effects are found on the steric shape of the blood vessel which is formed after the operation which will result in obstruction of the blood stream by preparing a model of the shape of the blood vessel of the patient for the operation and testing the type, the number and the position of placement of the clip or the position and the method of placement of a coil or the like, since it enables to conduct the optimum treatment using a clip, a coil or a stent rapidly in the operation.
As the model for the preoperative simulation, the present inventor has proposed a method for producing a human bone model for simulation of the operation in accordance with the lamination modeling method in which the model is divided into thin layers and each thin layer is formed by sintering a powder material with laser (Patent Reference 1).
However, in accordance with the above method, a model of the human bone is formed with a material which has approximately the same hardness as that of the human bone and can be cut as easily as the human bone. A model of a flexible vascular shape such as a model of a blood vessel, which is the subject of the present invention, cannot be prepared in accordance with the above method.
When a vascular shape is formed in accordance with the method of preparing a hard model as described above, the model is suitable for understanding the steric relation of the positions of the affected part and the blood vessel and examining the direction of the operation, e.g., the direction of inserting a clip. However, the effect of the operation on the shape of the blood vessel after the operation has been completed cannot be confirmed. Moreover, the simulation cannot be conducted under the condition such that a coil or a stent is inserted at the inside.
No references which provide a model of a hollow tubular shape of a flexible portion for the operation such as a blood vessel can be found heretofore.
[Patent Reference 1] Japanese Patent No. 3927487